This is a strange dialogue. Lightroom doesn't alter pixels 'cos a RAW file doesn't have any pixels. ACR likewise doesn't create a pixel based file till you exit it.

A RAW file has to have pixel data. That is basically what it has captured from the pixels in your sensor. Just look at the metadata for a RAW file, and it will tell you the height and width in pixels, and total pixels. What it doesn't have is a physical dimension such as inches. So there is no resolution in pixels per inch, just dimensions in pixels.

RAW processing is the business of assembling groups of red-green-blue pixel data from your camera's sensor into single pixels of a given color.

I think we said the same thing. My only point was that the RAW file contains pixel data. All the rest is very interesting, but not relevant to the point that the camera sensor captures pixel data, and the RAW file is a digital recording of it.

No. We are not saying the same thing.

You seem to think Bayer RAW "pixel data" and interpolated raster "pixel data" are basically the same idea or concept. They aren't. You're talking about entirely different kinds of pixels employed for entirely different purposes, manipulated in entirely different ways.

It's not "irrelevant" that Bayer RAW data, if you could "see" it, would look nothing like an interpolated raster image. It's not "irrelevant" that the tools one might use to manipulate such different kinds of data work differently, produce different results, for different reasons.

You're caught up on the word "pixel," here, and choosing not to see the forest for the trees. Your argument is essentially this: "Any language that uses the roman alphabet is really just the same language. It's all just letters."

Actually... you seem to be under a misconception MiraShootsNikon. While it is true that the RAW processors interpolate the RAW data, this is done as the very first step. So essentially, step one is to take any language using the Roman alphabet and translate it, after that it's all the same language and worked with the same way. In other words, they do end up being manipulated in exactly the same way with differences being only in that first interpolation step, which I have not seen any RAW developer expose any user adjustable options for. Dave Stott is a bit off the mark, RAW editors do not create an image file until exported, but they do keep a rasterized intermediate file in RAM which is what all the manipulations occur on that is based on as you say "interpolated raster pixel data." So yes, lightroom does alter pixel data, just not of the source (and neither does any other program as long as you don't overwrite your original file). If you don't believe me you can go look at the source code of some of the open source RAW converters (and yes, I am quite sure the closed source ones are not doing things drastically differently).

But I think, ttbek, that you aren't giving Mira enough credit. For two reasons:

(a) Her original post, above, did observe that both Lightroom and ACR generate a raster preview that reflects changes made as users employ them; and

(b) your post *assumes* that proprietary converters don't perform operations any differently than the open source code you've seen--but if that were true, then proprietary conversions wouldn't look so much better than most of the open source conversions I have seen!

Frankly, I don't believe it that Lightroom or ACR work as you say--that they make a raster conversion and then simply push the pixels of that conversion according to your edits. And here's my evidence: if what you say were true, then Lightroom's heal / clone operations could look identical to those from Photoshop. But Adobe has gone on record many times saying that Lightroom's clone-heal operations are limited to what they can currently process from RAW interpolation. They aren't in other words, simply pushing pixels on a raster intermediate. Sure, that's what's happening with the preview you see in the program itself, but when you export, your changes are actually baked straight from a novel RAW interpolation.